基于PIV的渐变地表粗糙度对坡面流水动力特性的影响
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谷方正(1999-),男,在读硕士研究生,主要从事水土保持研究。E-mail:mgu999@bjfu.edu.cn

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国家自然科学基金项目(52279056);“十四五”重点研发计划项目(2022YFF130009505)


The Influence of Gradient Surface Roughness on the Hydrodynamic Characteristics of Overland Flow Based on PIV
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    摘要:

    粗糙度是影响坡面流水动力特性的关键因子,为探究渐变粗糙度影响下坡面流水力特性,采用粒子图像测速技术(particle image velocimetry, PIV)观测并分析3组流量下渐变粗糙床面下坡面流的流速轮廓线、紊动强度、雷诺应力和壁面切应力的变化规律。结果表明:(1)流速随粗糙度增加而减小;拟合无量纲流速得到流速分布对数公式,粗糙度增大与拟合常数A成反比,与积分系数B成正比。(2)渐变地表粗糙度流向紊动强度与光滑床面坡面流变化趋势相似。流向紊动强度随相对水深的增大而减小。随着粗糙度增大,流向紊动强度大小出现非显著性差异。渐变粗糙床面下流向紊动强度符合Nezu经验公式,流量与经验系数成正比。(3)不同流量下,渐变粗糙床面的雷诺应力分布与光滑床面相似。在粗糙度影响下,雷诺应力最大值出现在y/H=0.2~0.4处。随着粗糙度逐渐增加,壁面切应力逐渐增大。综合表明,增加PIV分辨率方法可以适用于坡面流水力特性的研究。探究渐变粗糙度对坡面流的影响,探讨坡面流水动力学特性,为水土保持理论研究提供新思路。

    Abstract:

    Roughness is a key factor affecting the hydrodynamic characteristics of overland flow. In order to explore the hydraulic characteristics of overland flow under the influence of gradient roughness, using particle image velocimetry (PIV) to observe and analyze the velocity profile, turbulence intensity, Reynolds stress and wall shear stress of the overland flow under the three groups of flow rates. The results showed that: (1) The flow velocity decreased with the increase of roughness; the logarithmic formula of velocity distribution was obtained by fitting the dimensionless velocity. The increase of roughness was inversely proportional to the fitting constant A and proportional to the integral coefficient B. (2) The trend of streamwise turbulence intensity of gradient surface roughness was similar to that of smooth bed slope. The streamwise turbulence intensity decreased with the increase of relative water depth. With the increase of roughness, there was a nonsignificant difference in the intensity of streamwise turbulence. The turbulence intensity under the gradient rough bed was consistent with the Nezu empirical formula, and the flow rate was proportional to the empirical coefficient. (3) Under different flow rates, the Reynolds stress distribution of the graded rough bed was similar to that of the smooth bed. Under the influence of roughness, the maximum Reynolds stress appeared at y/H = 0.2~0.4. With the increase of roughness, the wall shear stress increased gradually. The synthesis showed that the method of increasing PIV resolution could be applied to the study of hydraulic characteristics of overland flow. Exploring the influence of gradient roughness on slope flow and exploring the hydrodynamic characteristics of slope flow provide new ideas for theoretical research of soil and water conservation.

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谷方正, 张会兰, 王铃涵, 夏绍钦, 孙虎.基于PIV的渐变地表粗糙度对坡面流水动力特性的影响[J].水土保持学报,2023,37(6):18~24,33

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  • 收稿日期:2023-05-22
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  • 在线发布日期: 2023-12-27
  • 出版日期: 2023-12-28